In recent years, for the purpose of global environment conservation, a refrigerant compressor with a higher efficiency, which can reduce the use of fossil fuel, has been developed.
One approach for achievement of the higher efficiency of the refrigerant compressor is, for example, formation of a phosphate coating film on a slide surface of a slide section such as a piston or a crankshaft to prevent abrasion of the slide section. By forming this phosphate coating film, unevenness of the processed surface of a machine processing finish can be removed, and initial conformability between slide members can be improved (e.g., see Patent Literature 1).
FIG. 8 is a cross-sectional view of a conventional refrigerant compressor disclosed in Patent Literature 1. As shown in FIG. 8, a sealed container 1 is an outer casing of the refrigerant compressor. Lubricating oil 2 is reserved in the bottom portion of the sealed container 1. The sealed container 1 accommodates therein an electric component 5 including a stator 3 and a rotor 4, and a reciprocating compression component 6 driven by the electric component 5.
The compression component 6 includes a crankshaft 7, a cylinder block 11, a piston 15, and the like. The configuration of the compression component 6 will be described below.
The crankshaft 7 includes at least a main shaft section 8 to which the rotor 4 is pressingly secured, and an eccentric shaft 9 which is provided eccentrically with the main shaft section 8. The crankshaft 7 is provided with an oil feeding pump 10.
The cylinder block 11 forms a compression chamber 13 including a bore 12 with a substantially cylindrical shape and includes a bearing section 14 supporting the main shaft section 8.
The piston 15 is loosely fitted into the bore 12 with a clearance. The piston 15 is coupled to the eccentric shaft 9 via a connecting rod 17 as a coupling means by use of a piston pin 16. The end surface of the bore 12 is closed by a valve plate 18.
A head 19 is secured to the valve plate 18 on a side opposite to the bore 12. The head 19 constitute a high-pressure chamber. A suction tube 20 is secured to the sealed container 1 and connected to a low-pressure side (not shown) of a refrigeration cycle. The suction tube 20 leads a refrigerant gas (not shown) to the inside of the sealed container 1. A suction muffler 21 is retained between the valve plate 18 and the head 19.
The main shaft section 8 of the crankshaft 7 and the bearing section 14, the piston 15 and the bore 12, the piston pin 16 and the connecting rod 17, the eccentric shaft 9 of the crankshaft 7 and the connecting rod 17 constitute slide sections.
In a combination of the iron-based materials among the slide members constituting the slide sections, as described above, an insoluble phosphate coating film comprising a porous crystalline body is provided on the slide surface of one of the iron-based materials.
Next, the operation of the sealed compressor having the above-described configuration will be described. Electric power is supplied from a power supply utility (not shown) to the electric component 5, to rotate the rotor 4 of the electric component 5. The rotor 4 rotates the crankshaft 7. By an eccentric motion of the eccentric shaft 9, the piston 15 is driven via the connecting rod 17 as a coupling means and the piston pin 16. The piston 15 reciprocates inside the bore 12. By the reciprocating motion of the piston 15, a refrigerant gas is led to the inside of the sealed container 1 through the suction tube 20, suctioned from the suction muffler 21 into the compression chamber 13, and compressed inside the compression chamber 13 in succession.
According to the rotation of the crankshaft 7, the lubricating oil 2 is fed to the slide sections by the oil feeding pump 10, and lubricates each of the slide sections. In addition, the lubricating oil 2 serves to seal a gap formed between the piston 15 and the bore 12.
The main shaft section 8 of the crankshaft 7 and the bearing section 14 perform a rotation. While the refrigerant compressor is stopped, a rotational speed is 0 m/s. During start-up of the refrigerant compressor, the rotation starts in a state in which the metals are in contact with each other, and a great frictional resistance force is generated. In this refrigerant compressor, the phosphate coating film is provided on the main shaft section 8 of the crankshaft 7, and has an initial conformability. In this structure, the phosphate coating film can prevent an abnormal abrasion caused by the contact between the metals during start-up of the refrigerant compressor.